Accelerometer



May 29, 1945.

` R. B. COTTRELL.

ACCELEROMETER Filed DSC. 50, 1943 2 lSheets-Sheet 2 INVENTOR. @MQ/jij? @af/gaf Patented May 29, 1945 UNITED STATES PATENT QFFICE ACCELEROMETER Robert B. Cottrell, Chicago, Ill., assignor to American Steel Foundries, Chicago, Ill., a corporation of New Jersey Application December 3o, 1943, serial No. 516,175

6 Claims. (Cl. 264-1) My invention relates to a measuring device and more particularly to an instrument for measuring movements or changes in velocity of a movable object, such an instrument being comof the sleeve I6, said nuts being received within recesses 22, 22 formed in the respective members I4, I4.

A vertical strap 24 is connected at ts lower A. ing 30 in the frame and being adjustably secured thereto by means of an adjusting nut 32 monly known as an accelerometer. 5 and a lock nut 34 in threaded engagement with 'The general object of my invention is to design the upper end of said strap 24. an accelerometer in which a mass is suspended Four horizontal straps, 86, 88, 40 and 42 are from a frame by means of ai plurality of tension pivotally connected at their corresponding ends straps, each strap being provided with a device, as at 44', 46, 48 and 50, respectively, to the spider such as a strain gauge, for measuring changes l0 I8, and the opposite corresponding ends of said in the tension thereof due to relative movement straps project respectively through openings 52, between the mass and the frame. 54, 56 and 58 formed in the frame for threaded A further object of my invention is to design engagement with adjusting nuts 60, 60 and lock an accelerometer such as above described in nuts 82. 62 by means of which each strap may which'the tension, straps are connected to the .l5 be placed under adjustable tenSiOn. mass at substantially the centerof gravity there- Each strap is provided with an electric strain of. gauge 64, and it will be understood by those In the drawings, l* skilled in the art that the strain gauge consists Figure 1 is a top view of my novel acceleroi` a loop of extremely iine wire fixed to the ometer, the upper half of Figure 1 being a top 20 strap by means of a piece of cloth or paper inplan view and the lower half thereof being a dicated at 66, current'being passed through this sectional view with portions of thestructure loop by means of two leads 68 and 10. Thus, shown in section along the plane indicated by as the tension of the strap varies, the resistance the line I-I of Figure 2. I f v' of the strain gauge wire also varies and is regis- Figure 2 is a sectional view taken in the planes 25 tered on a recording instrument, such as an oscilindicated by the line 2--2 of Figure 1. loscope, connected to the leads 6B and 10. The

Figure 3 is a. sectional view comparable to Figstrain gauge 64 is of conventional form and is ure 2, but illustrates a modication of my intherefore not illustrated in detail in the present vention. application.

Describing my invention in detail and refer- 30 It will be understood that the mass I2 is susring first to the embodiment `illustrated in Figpended within the frame 2 by means 0f the Sbrps ures 1 and 2, the frame, generally designated 2, 24, 33. 33, 40 and 42, euch 0f Said Straps being comprises four columns 4, 4, joining each other adjustably tensioned by means 0f the associated at their upper extremities and merging at their adjusting nut 60. Thus, vertical movement of lower extremities with a base 6 affording a seat 35 the mass I2 with respect to the frame 2 is regisfor the accelerometer upon yan associated moving tered by means of the strain gauge associated object, said base being provided with spaced with the vertical strap 24, some registration bebosses 8, 8 and openings I0, I0 therethrough for ing recorded by the strain gauges associated the reception of any convenient securing means. with the other straps. Movement of..l the mass Such as bolts, whereby Said frame may be Se- 4 l2 to the right orloft, as soon in Figure 1, w111 be Cured t0 the moving Object primarily registered by the strain gauges asso- Suspnded Centralb 29f Sel? feme is a iPass oiod with the straps ss' and 4o with some regisljd' a "orl, onfaapll'eg tration on the strain gauges associated with the I6 extending through central aligned openings 45 hfr brie strass and movemept o.: the mass in the members I4 I4 and passing through the o e .Op or Ottom' as seen m .Figure 1 Wm be primarily registered by the strain gauges ascenter of gravity of the mass I2. Mounted on the sleeve I6 is a collar or spider I8 against l soclated with the straps 38 and 42, some reg1s- /which the semispheres I4, I4 are maintained by Matton bemg afforded by the other three Strapsmeans of nuts 20, 2li/threaded on opposite ends 50 It Wm be understood that by a Process 0f Calibration it can vreadily be determined to what extent movement in each direction is recorded by the various strain gauges and thus, when the device is in operation, movements or changes in'y end to the sleeve I6 by means of a bolt'and nut 55 velocity of the moving object to which the frame 2 is attached may be determined by means of my novel accelerometer.

The connection of the strap 24 to the sleeve |6 is at the center of gravity of the mass I2 and,

.likewisa the connection of each strap 36, 38, 40

and 42 to the spider I8 is closely adjacentthe center of gravity of the mass, and it will be understood that inasmuch as there is a concentra-v tion of the weight of the mass at the center of gravity thereof, this arrangement is of considerable signiiicance in affording delicate response of the device to movements of the object to which the frame 2 is attached.

Referring now to Figure 3, the accelerorneter illustrated therein is substantially identical with that shown in Figures 1 and 2, except for the addition of a lower vertical tension strap |02 disposed in opposed relationship with respect to the upper vertical tension strap 24. The lower strap is provided with a strain gauge |04, an adjusting nut |06 and a locking nut |08. It will be understood that the provision of the lower strap |02 facilitates adjustment of the tension on the strap 24 and also affords additional registration of vertical movements of the mass I2 by means of the strain gauge |04.

It is to be understood that I do not wish to be limited by the exact embodiments of the device shown which are merely by way of illustration and not limitation as various and other forms of the device will, of course, be apparent to those skilled in the art without departing from the spirit of the invention or the scope of the claims.

I claim:

1. A device including a frame, a mass consisting of two spaced semispheres joined by a sleeve extending through the center of gravity of said mass, a spider mounted on said sleeve between said spaced semispheres, two pairs of horizontal n straps connected to said spider and said frame, a'

vertical strap connected to said frame and to said sleeve at substantially the center of gravity of said mass mass, strain gauges on said straps for measuring changes in the tension, thereof, and

means on each strap for adjustably varying the tension thereof.

2. A device including a frame, a mass consisting of two spaced semispheres `ioined by a sleeve extending through the center of gravity of said mass, a spider mounted on said sleeve intermediate said spaced semispheres, two pairs of horizontal tension straps connected to said spider and said frame, upper and lower vertical tension straps connected to said frame and connected to said sleeve at substantially the center of gravity of said mass, and strain gauges on said straps for measuring changes in the tension thereof.

3. A device including a frame, a mass consisting of two spaced semispheres joined by a sleeve extending through the center of gravity of said mass, a spider mounted on said sleeve between said spaced semispheres, two pairs of horizontal straps connected to said spider and said frame, a vertical strap connected to said frame and to said sleeve at substantially the center of gravity of said mass, and means for registering changes in the tension of said straps.

4. A device including a frame, two pairs of horizontally disposed tension straps, a substantially vertical strap, a mass suspended by said straps, and means for indicating changes in the tension of said straps, all of said straps being connected to said mass at substantially the center of gravity thereof.

5. A device including a frame, a mass suspended therein by means of a plurality of tension straps connectedto said mass and adjustably connected to said frame, and means associated with each strap for indicating changes in the tension thereof, the connection of said straps to said mass being at approximately the center of gravity thereof.

6. A device including a frame, a mass supported from said frame and relatively movable with respect thereto, a tension strap connected to said mass and said frame, and means for indicating changes in the tension of said strap.

ROBERT B. COTTRELL. 

